Researchers Use Carbon Fiber Waste to Strengthen Permeable Pavement

Researchers from Washington State University have shown permeable concrete can be strengthened by adding recycled carbon fiber.

The production of carbon fiber goods is on the rise; however, recycling this material still remains a challenge. It may, however, be soon possible to grind up carbon fiber waste and use it in water-draining concrete, according to a research being conducted at Washington State University.

Water-draining concrete or pervious concrete is a kind of concrete that stormwater run can drain straight through. It is a highly porous material and allows the water to pass into the soil underneath. This helps with flooding but also reduces pollution caused by stormwater.

With traditional concrete, the water will run along the road and gather pollutants, before it goes down a sewer and into the waterways.

There has been rising concern about flooding in urban areas and requirements for controlling stormwater have increased.

Several cities have so far tried using pervious concrete in parking lots and streets with low-traffic. However, because it is highly porous, it has proved not as durable as the regular concrete used on major roads. Carbon fiber helps in this aspect.

Carbon fiber becoming more popular

Carbon fiber composites have become steadily more popular in various industries. The material is super light and strong. It can be used in a variety of places ranging from airplane wings to wind turbines and cars. The market has been growing about 10 percent per year, and industries have been trying to find out a way to recycle the waste.

The research team from Washington State University found a method to recycle this waste and put it to good use.

To grind up scrap carbon fiber provided by Boeing, the research team used an inexpensive mechanical milling technique. When ground carbon fiber was added to the existing pervious concrete mix, the resulting material ended up being very durable and strong.

"In terms of bending strength, we got really good results — as high as traditional concrete, and it still drains really quickly," said Somayeh Nassiri, who led the research team along with Karl Englund.

Left in cured form

The researchers shun using heat or chemicals to create an element from the waste carbon fiber composites. They kept the composites in their cured form maintained and thus made use of their original strength.

The mix also required using much of the composite material. This would be ideal for waste producers.

“You’re already taking waste — you can’t add a bunch of money to garbage and get a product,” said Englund. “The key is to minimize the energy and to keep costs down.”

The composite materials were scattered through the pavement mix to give stable strength. The effectiveness of the technology has been shown on laboratory samples, and scientists wish to now conduct large-scale tests.

The researchers are also working with industry to develop a supply chain. “In the lab this works to increase permeable pavement’s durability and strength,” said Nassiri. “The next step is to find out how to make it mainstream and widespread.”

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